[sdiy] A20G545 chip, what is it?

John Speth johnspeth at yahoo.com
Sun Jun 19 16:54:08 CEST 2022

 I don't think it was an LM389 (audio power amp) but that got me thinking: Could it be a mismarked SSM2033? The pin count matches and the power connections (the only connections wired) are consistent with the data sheet. Sometimes shipments to manufacturers are marked according to the buyer's specs (obfuscation, custom variation, etc). I can't remember from whom I was buying my small quantity SSM chips at the time. There were not a lot of retail mail order sellers back then. - JJS
    On Sunday, June 19, 2022, 07:14:38 AM PDT, Mike Bryant <mbryant at futurehorizons.com> wrote:  
Possibly an LM389 transistor array equivalent
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org]On Behalf Of John Speth via Synth-diy
Sent: 19 June 2022 14:58
Subject: Re: [sdiy] A20G545 chip, what is it?
Photo at: https://myplace.frontier.com/~jspeth/A20G545.JPG
I should have posted this pic first. The date code accurately indicates when I built it: 1983. So anything with origins past that date are not valid. 
Thanks - JJS
On Sunday, June 19, 2022, 06:05:02 AM PDT, <synth1 at airmail.net> wrote:
I'm pretty good at this if I can SEE a photo.

Paul S.

-----Original Message-----
From: Synth-diy <synth-diy-bounces at synth-diy.org> On Behalf Of brianw
Sent: Sunday, June 19, 2022 3:16 AM
To: John Speth <johnspeth at yahoo.com>
Cc: SDIY <synth-diy at synth-diy.org>
Subject: Re: [sdiy] A20G545 chip, what is it?

My first guess was a 74x545 octal bidirectional transceiver, non-inverting.
They're 20-pin.

However, that doesn't seem to fit on a SSM voice card (or into an 18-pin


On Jun 18, 2022, at 7:59 PM, John Speth wrote:
> Today I was dumping old circuit boards that I built many years ago. I was
stripping valuable parts from one and I found two 18 pin DIPs that are
marked "A20G545" on one line and "MCE 8211" on the line below it. 8211 is
the date code (1982). The other markings are a mystery. Searching for this
chip online was a dead end for me. Does anybody know what it could be? It
was from a board that contained an SSM 2012 VCA and an SSM 2044 VCF. I've
lost the schematics. It was my design.
> Thanks - JJS

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